中文摘要：

对川中丘陵区典型小流域地下水N素含量及形态分配的监测结果表明，硝酸盐（NO3^--N）是该地区地下水N索存在的主要形态。川中丘陵区54．5％的地下水NO3^--N含量超过世界卫生组织（WHO）饮用水准则规定的10mg·L^-1标准，另有27．3％的地下水NO3^--N含量接近这一标准，表明该区地下水已经大范围地受到NO3^--N污染的威胁。土地利用状况可能是影响川中丘陵区地下水NO3^--N含量的主要因素。降雨量和水井深度也影响该区地下水NO3^--N含量。紫色土坡耕地NO3^--N随壤中流向浅层地下水迁移，可能是造成该区地下水NO3^--N含量较高的最重要原因。

英文摘要：

Forms and contents of N pollutants in groundwater in a typical small watershed in the hilly area of the Central Sichuan Basin were monitored for a year. Results show that nitrate was the main form of nitrogen in groundwater in the watershed. The content of nitrate-nitrogen in 54.5% of the monitored wells was found above 10 mg·L^-1 （ drinking water standard of WHO）, and 27.3% approaching 10 mg·L^-1 , suggesting that nitrate pollution had occurred in a large area in the hilly region of the Central Sichuan Basin. Land use is the main contributor of NO3^--N content in the groundwater, and precipitation and well depth are also affecting factors. In slope cropland of purple soil, nitrate accumulated in the plow layer moving down into subsurface flow could be the major source of the higher content of nitrate in the groundwater.